1. Related Applications
This application is related to U.S. application Ser. No. 11/687,571 to Lee et al., entitled “Chassis Partition Architecture for Multi-processor System” filed concurrently herewith, and which is herein incorporated by reference.
2. Field of Invention
The present invention relates to the physical hardware architecture of a multi-processor system, and more particularly, to a multidirectional configurable architecture for a multi-processor system.
3. Related Art
For a multi-processor system with processors configured on plural printed circuit boards, traditional electronic enclosure design requires a complex and expensive internal chassis with many routed cables therein to provide mechanical support for the electronic components. The requirements for variable types of IO devices and storage unit including hot swapping plus airflow for cooling further increase the complexity of the system design. This complexity increases the overall sides of the system and in some cases limits some configurable options to be part of the “base architecture”, which is dictated by the overall dimensions of the chassis and internal structure. One example is the difficulty in servicing the center interconnecting plane. Most backplane and mid-plane designs in the prior art are not field serviceable due to difficulty or no access in the assembled chassis. Another example is the difficulty to provide sufficient cooling and airflow to the various components due to blockage as a result of the placement of the different parts of the system. Besides, once numerous function cards need to be configured on the system, it becomes much more difficult to fulfill the requirements of cooling, serviceability and hardware reliability. For high-end systems, flexibility will be another critical issue.
Basically, there are two major factors to decide the configurable directions or serviceability of a computing system. First of all, the way of physical division decides how the hardware components of the computing system are separated into subsystem boards. The other is the connection types between these subsystem boards. Both the physical division for hardware components and the connection types of subsystem boards affect the cooling performance and hardware reliability. Although theoretically the more the subsystem boards are divided, the higher the system flexibility will be. However, the physical division is still limited by actual hardware capabilities.
As shown in FIG. 1, the front portion in a chassis 10 of a clustering system is configured with plural mainboards (mother boards) 11. The lower half of the rear portion in the chassis 10 is configured with one or more power supply 12 that has dedicated fan(s); however, the power supply 12 at the lower portion is still a blockage for the main air flow generated by several main fans 13 at the upper portion. Since the airflow has to pass the power supply 12 through small fan(s), the flow rate through the power supply 12 is usually smaller than the main fans 13. Therefore, the processors 110 are configured at upper positions. In such simple system, the mainboards 11 slides inwards/outwards through the front side of the chassis 10 so it is only front-side serviceable and configurable. Generally the chassis 10 has predetermined access holes to allow human hands reaching inside.
FIG. 2 shows an 8-way system. Four processors 210 with dedicated system memories 211 are configured on each of the two stacked processor boards 21. Between the two processor boards 21, two system bus cards 22 are used for board-to-board connection through connectors 212. Such system obviously is top-side serviceable and configurable due to its hardware architecture. Engineers have to remove the upper processor boards 21 to access the lower processor boards 21 and the two system bus cards 22.
FIG. 3 shows another 8-way system 3, which includes four dual-processor cards 31 configured on a baseboard 32, and an input/output board 33 engaged with the baseboard 32 through several edge connectors 34. Each of the four dual-processor cards 31 faces another two by two, with one or more fan 35 configured between each pair of four dual-processor cards 31. Expansion card(s) 331, I/O controller(s) 332 and bridge chips 333 are located on the input/output board 33. The cooling problem in such “flat” system is that the sizes of the fans 35 is relatively smaller, which require high rotation speed to carry away the heat efficiently. However, the higher the fan speed increases, the more the fan noise occurs. Besides, although such system has overall two or three serviceable/configurable sides (the two lengthwise sides and the top side), the cooling, serviceability and reliability problems will still occur when extra function cards (not shown) are added on the system architecture.
If the extra function cards are arranged lengthwise (following the directions of the dual-processor cards 31), the system will has a strange flat, long structure and the flow paths will be too long to dissipate heat efficiently. If the extra function cards are arranged widthwise (parallel to the expansion card(s) 331), the trace lengths on the input/output board 33 might be too long to meet bus communication requirements. Plus the arrangement of blockage units like hard drives, the architecture becomes extremely complicated.